Rig Glossary: H–L


Hanging-Line Cable Clamps

Steel line clamps used to secure the steel cable to the tongs and the tong counter-weight.


Hardfaced alloys that were welded onto drill pipe tool joints, collars and heavy-weight pipe in order to protect the drill string and drilling assets from wear associated with the drilling practices. Hardbanding is usually applied to the outer box end of drill pipe tool joints.

Heavy-Weight Drill Pipe

Like drill pipe, but with a heavier walled thickness and stiffer, used for a flexible transition between the drill collars and the drill pipe.

Hinge Pin Cotter Key

A double legged retaining pin that once in the hole of a pin, the legs are parted to secure the key in the hole.

Hobble Strap

A strap attached to the left horn of the elevators to hold them in a horizontal position when the Derrickhand closes the elevators around a tubular stand.

Hoisting Clutch

An air clutch that engages power to the drawworks to hoist the drill string.

Hold Back Ropes

Ropes attached at the V-Door to assist in handling tubulars once they are hoisted to the rig floor from the catwalk.


A large, hook-shaped device from which the elevator bales or the swivel is suspended. It turns on bearings in its supporting housing.



A large funnel or cone-shaped device mounted in the mud tank circulating system into which dry chemicals (gel or barite) can be poured to mix uniformly with the drilling mud. The dry component is introduced through a jet nozzle at the bottom of the hopper.

Horn Retaining Knob (Elevator)

A half inch protruding knob on the underside of the left elevator handle that prevents the hobble strap from sliding off the horn.


Protruding handles from the body of the elevators used to open, close or stabilize the elevators.

Hydraulically Controlled Remote (HCR) Valve

A valve remotely operated to control the release of fluids and pressure from the well bore to a choking device or bleed-off line. There are usually at least two valves connecting the BOP stack to the manifold. One is a HCR the other is a manually operated valve that is kept in the open position and is used as a backup for the HCR.


Inland Barge Rig

An off shore drilling structure consisting of a barge on which the drilling equipment is constructed. It is positioned on location, and then the barge is lowered.

Intermediate Casing String

The string of casing set in a well after the surface casing but before production casing is set to keep the hole from caving and to seal off formations. In deep wells, one or more intermediate strings may be required.

Iron Roughneck/Hydraulic Wrench

A remotely controlled piece of equipment that makes up or breaks down pipe using a rotary table and torque wrench(es).




A percussion tool operated manually or hydraulically to deliver a heavy upward or downward blow to fish stuck in the borehole. To apply a heavy blow to the drill stem by use of a jar or bumper sub.

Jaw Latch

A segment of the tong that engages the tong jaw.


A length of drill pipe or casing. Both come in various lengths.

Junk Basket

A device made up on the bottom of the drill stem or on wireline to catch pieces of junk from the bottom of the hole. Circulating the mud or reeling in the wireline forces the junk into a barrel in the tool, where it is caught and held. When the basket is brought back to the surface, the junk is removed. Also called a “junk sub” or “junk catcher”.




The heavy square or hexagonal hollow steel member is attached to the swivel and runs through the rotary table and connected to the topmost joint of drillpipe. The rotary table turns the kelly which then turns and sends torque from the rotary table to the drill string and on to the drill bit (the kelly is the only part of the drill string that can be both above and below the rotary table during drilling).

Kelly Bushing (KB)

A device fitted to the rotary table through which the kelly passes and the means by which the torque of the rotary table is transmitted to the kelly and to the drill string. Also called the “drive bushing”. Depth measurements are commonly referenced to the KB, such as ft or m KB, meaning feet or metres below the kelly bushing.

Kelly Hose

A flexible high pressure hose that connects the swivel to the standpipe. It must be flexible so it is able to move up and down with the travelling blocks or move with swivel movements.

Kelly Spinner

A pneumatically or hydraulically operated device mounted on top of the kelly that, when actuated, causes the kelly to turn or spin.

Kicker Hose

A high-pressure rubber hose that connects the mud pump discharge line to the mud line that runs along and inside the rig substructure. The kicker hose has wire braiding in its rubber structure. Also called a “Shock Hose” or “Kick Hose”.

Kill Line

A high-pressure pipe leading from an outlet on the BOP stack to the high-pressure rig pumps. During normal well control operations, kill fluid is pumped through the drill string and annular fluid is taken out of the well through the choke line to the choke, which drops the fluid pressure to atmospheric pressure.



Land Rig

Any drilling rig that is located on dry land.

Latch On

To attach elevators to the upper section of drillpipe to pull it out of or run into the hole.

Latch Spring

A spring that is placed between a tong jaw and tong latch to help maintain the tong latch in a positive engagement with the tong jaw.

Lay Down Pipe

To pull drill pipe from the hole and lay it down on the catwalk.

Lifting Nubbin

A device to attach to a tubular threaded box end or special tools pin end to enable the safe lifting of the tubular usually to the rig floor.

Lifting Sub

A short sub screwed into drill collars to allow drill pipe elevators to latch onto the larger diameter drill collars; also called “pick-up sub”.

Line Guide

A system used to help control spooling the line on the drum.

Line On The Drum

Steel braided wire cable wound around the drum of a winch.

Line Spooler Handle

A device used to control the orderly placement of wireline wraps around the tugger winchline drum, to prevent the line from becoming tangled or crossed over.

Lock Out System

A system used to isolate a piece of equipment from its power source.

Lower Kelly Cock

A ball valve installed at one end of the kelly that can be used to stop mud draining from the kelly during a connection.A pneumatically or hydraulically operated device mounted on top of the kelly that, when actuated, causes the kelly to turn or spin.

Courtesy of Ensign Drilling Inc.